Sensor with low power with closed-loop-force-feedback loop

ABSTRACT

A device includes a proof mass of a sensor, capacitive elements, an electrode circuitry, a time multiplexing circuitry, a sense circuitry, and a force feedback circuitry. The proof mass moves from a first position to a second position responsive to an external actuation. The capacitive elements change capacitive charge in response thereto. The electrode circuitry coupled to the capacitive elements generates a charge signal. The time multiplexing circuitry pass the charge signal during a sensing time period and prevents the charge signal from passing through during a forcing time period. The sense circuitry generates a sensed signal from the charge signal. The force feedback circuitry applies a charge associated with the sensed signal to the electrode circuitry during the forcing time period. The electrode circuitry applies the charge received from the force feedback circuitry to the capacitive elements, moving the proof mass from the second position to another position.

RELATED APPLICATIONS

This application is a divisional application and claims the benefit andpriority to the nonprovisional patent application Ser. No. 15/265,740,filed on Sep. 14, 2016, which claims the benefit and priority to theprovisional patent application No. 62/361,428, filed on Jul. 12, 2016,entitled “System and method for MEMS gyroscope force-feedback using lowpower time-interleaving techniques,” which are incorporated herein byreference in their entirety.

BACKGROUND

Many gyroscopes use open loop architecture to directly measure output ofa micro-electro-mechanical systems (MEMS). Unfortunately, open looparchitecture suffers from stability due to environmental factors such astemperature and strain as well as aging. In contrast, closed looparchitecture such as closed-loop-force-feedback architecture can be usedto actuate the sense resonator to cancel out the movement induced by therate of rotation and to use the feedback signal as a measure of thegyroscope's input. While the closed-loop-force-feedback architecture ismore stable it traditionally requires high voltage drivers and resultsin an increased system power consumption which is undesirable.

SUMMARY

Accordingly, a need has arisen to develop a stableclosed-loop-force-feedback architecture with minimal impact on systempower consumption. Moreover, a need has arisen to develop a stableclosed-loop-force-feedback architecture that enables mode matchingdesign where the drive and sense resonators have the same resonancefrequency. It is further desirable to develop a stableclosed-loop-force-feedback architecture with flexibility of calibratingthe gyroscope's bias, e.g., offset, and its sensitivity, e.g., gain,over time and temperature or other ambient variability.

In some embodiments, the sense electrodes of the gyroscope may be usedfor both actuation and sensing. According to some embodiments, thesensed signal is time multiplexed and charges associated with the timemultiplexed signal is determined. During a forcing time period thedetermined charges are applied to the sense electrodes which apply thecharges to the capacitive elements that force the proof mass back to itsinitial position.

According to some embodiments, a device includes a proof mass associatedwith a sensor, capacitive elements, an electrode circuitry, a timemultiplexing circuitry, a sense circuitry, and a force feedbackcircuitry. The proof mass is configured to move from a first position toa second position in response to application of an external actuation,e.g., force, rotation, etc. The capacitive elements are configured tochange capacitive charge stored thereon in response to the proof massmoving from the first position to the second position. The electrodecircuitry is coupled to the capacitive elements and is configured togenerate a charge signal thereof. The time multiplexing circuitry iscoupled to the electrode circuitry and is configured to pass the chargesignal during a sensing time period, in response to a control signal.The time multiplexing circuitry is further configured to prevent thepassing of the charge signal during a forcing time period, responsive tothe control signal. The sense circuitry is configured to receive thecharge signal from the time multiplexing circuitry during the sensingtime period and to generate a sensed signal. The force feedbackcircuitry is configured to apply a charge associated with the sensedsignal to the electrode circuitry during the forcing time period. Theapplication of the charge to the electrode circuitry is responsive tothe control signal. The electrode circuitry applies the charge receivedfrom the force feedback circuitry to the capacitive elements to move theproof mass from the second position to another position.

In some embodiments, the another position is a position between thefirst position and the second position. It is appreciated that theapplication of the charge received from the force feedback circuitry tothe capacitive elements moves the proof mass to the another position andreduce movement of the proof mass. In some embodiments, a velocityassociated with movement of the proof mass approaches zero over time inresponse to application of the charge by the electrode circuitry to thecapacitive elements. The sensor may be a gyroscope.

The capacitive elements may include a first and a second capacitor. Thecharges stored on the first capacitor changes in one polarity directionin response to the proof mass moving from the first position to thesecond position. The charges stored on the second capacitor changes inanother polarity direction in response to the proof mass moving from thefirst position to the second position. The change in polarity directionsof the first and the second capacitor are in opposite direction of oneanother.

The electrode circuitry may include a first and a second electrodes withopposite polarities. The time multiplexing circuitry may include aplurality of switches that open and close in response to the controlsignal. The force feedback circuitry may include a plurality of switchesthat open during the sensing time period and close during the forcingtime period.

The device may further include an amplifier coupled to the timemultiplexing circuitry that is configured to amplify the sensed signal.The device may also include an analog to digital convertor configured toconvert the amplified sensed signal to a digital signal. The device mayfurther include a digital signal processor (DSP) coupled to the analogto digital convertor configured to process the sensed signal and todetermine the charge associated with the sensed signal to be applied tothe electrode circuitry during the forcing time period. In someembodiments, the device includes a digital to analog convertor (DAC)coupled to the DSP. The DAC is configured to convert digital signal toanalog signal and to generate a force signal based on the determinedcharge associated with the sensed signal.

In some embodiments, the sensor may include a drive circuitry. The drivecircuitry may include an amplifier, an analog to digital convertor, adigital resonator, and a feedback loop. The amplifier is configured toamplify a drive signal. The analog to digital convertor is configured toconvert the amplified drive signal from analog signal to digital signal.The digital resonator is configured to resonate at a resonance frequencyto reduce error, e.g., phase error. The feedback loop is configured toreceive signal from the digital resonator and apply a feedback signal toan input of the amplifier. The feedback loop includes a digital toanalog convertor coupled in series with an optional capacitor.

These and other features and aspects of the concepts described hereinmay be better understood with reference to the following drawings,description, and appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a sense circuitry of a sensor in accordance with someembodiments.

FIGS. 2A-2C show alternative sense circuitry of a sensor in accordancewith some embodiments.

FIG. 3 shows yet another alternative sense circuitry of a sensor inaccordance with some embodiments.

FIG. 4 shows a drive circuitry of a sensor in accordance with someembodiments.

FIG. 5 shows an alternative drive circuitry of a sensor in accordancewith some embodiments.

FIGS. 6A-6B show a flow diagram for low power consumption force feedbackon the sense circuitry and drive circuitry respectively in accordancewith some embodiments.

FIG. 7 shows an exemplary simulation of a proof mass in accordance withsome embodiments.

DETAILED DESCRIPTION

Before various embodiments are described in greater detail, it should beunderstood by persons having ordinary skill in the art that theembodiments are not limiting, as elements in such embodiments may vary.It should likewise be understood that a particular embodiment describedand/or illustrated herein has elements which may be readily separatedfrom the particular embodiment and optionally combined with any ofseveral other embodiments or substituted for elements in any of severalother embodiments described herein.

It should also be understood by persons having ordinary skill in the artthat the terminology used herein is for the purpose of describing thecertain concepts, and the terminology is not intended to be limiting.Unless indicated otherwise, ordinal numbers (e.g., first, second, third,etc.) are used to distinguish or identify different elements or steps ina group of elements or steps, and do not supply a serial or numericallimitation on the elements or steps of the embodiments thereof. Forexample, “first,” “second,” and “third” elements or steps need notnecessarily appear in that order, and the embodiments thereof need notnecessarily be limited to three elements or steps. It should also beunderstood that, unless indicated otherwise, any labels such as “left,”“right,” “front,” “back,” “top,” “middle,” “bottom,” “forward,”“reverse,” “clockwise,” “counter clockwise,” “up,” “down,” or othersimilar terms such as “upper,” “lower,” “above,” “below,” “vertical,”“horizontal,” “proximal,” “distal,” and the like are used forconvenience and are not intended to imply, for example, any particularfixed location, orientation, or direction. Instead, such labels are usedto reflect, for example, relative location, orientation, or directions.It should also be understood that the singular forms of “a,” “an,” and“the” include plural references unless the context clearly dictatesotherwise.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by persons of ordinaryskill in the art to which the embodiments pertain.

A need has arisen to develop a stable closed-loop-force-feedbackarchitecture with minimal impact on system power consumption. Moreover,a need has arisen to develop a stable closed-loop-force-feedbackarchitecture that enables mode matching design where the drive and senseresonators have the same resonance frequency. It is further desirable todevelop a stable closed-loop-force-feedback architecture with theflexibility of calibrating the gyroscope's bias, e.g., offset, and itssensitivity, e.g., gain, over time and temperature or other ambientvariability.

In some embodiments, the sense electrodes of the gyroscope may be usedfor both actuation and sensing. According to some embodiments, thesensed signal is time multiplexed and charges associated with the timemultiplexed signal is determined. During a forcing time period thedetermined charges are applied to the sense electrodes which apply thecharges to the capacitive elements that force the proof mass toward itsinitial position.

Referring now to FIG. 1, a sense circuitry of a sensor in accordancewith some embodiments is shown. The sensor 100 may include a proof mass110, capacitive elements such as capacitors 112-114, an electrodecircuitry 120 (also referred to as sensing electrode), a timemultiplexing circuitry 130, a sense component 135, a processingcircuitry 137, and a force feedback circuitry 140.

The sensor may be a micro-electro-mechanical systems (MEMS) sensor suchas a gyroscope sensor. According to some embodiments, the proof mass 110may move in one direction or another in response to an externalactuation, e.g., rotation, movement, etc. For example, the proof mass110 may move up/down as shown by Δx. In other words, the proof mass 110moves from a first position to a second position in response toapplication of the external actuation, e.g., force, rotation, etc. Themovement of the proof mass 110 causes a change in charges stored on thecapacitors 112 and 114. For example, if the proof mass 110 moves up,then the charges stored on the capacitor 112 increases, e.g., +ΔQ, whilethe charges stored on the capacitor 114 decreases, e.g., −ΔQ. Similarly,if the proof mass 110 moves down, then the charges stored on thecapacitor 112 decreases e.g., −ΔQ, while the charges stored on thecapacitor 114 increases, e.g., +ΔQ. It is appreciated that the change inthe charges of the capacitors 112 and 114 may be the same but inopposite polarity if the capacitors 112 and 114 have the samecapacitance value. However, it is appreciated that the change in thecharges of the capacitors 112 and 114 may merely be in opposite polarityof one another but the change in the charge may not be the same.

The electrode circuitry 120 outputs a signal to the time multiplexingcircuitry 130. The signal is transmitted from the electrode circuitry120 to the time multiplexing circuitry 130 that is controlled by acontrol signal 142. During a sensing time period, the signal, e.g.,charge differential, is collected by the time multiplexing circuitry 130and transmitted to the sense component 135 to be sensed, e.g., timemultiplexed sensed signal 132. The time multiplexed sensed signal 132 istransmitted to the processing circuitry 137 to be processed, e.g.,modulation, demodulation, filtering, etc. For example, appropriatecharges to be applied to the electrode circuitry 120 during a forcingtime period based on the processed time multiplexed sensed signal 132may be determined and communicated to the force feedback circuitry 140.

During a forcing time period (non-sensing time period), the forcefeedback circuitry 140 applies the determined appropriate charges to theelectrode circuitry 120, in response to the control signal 142. In someoptional embodiments, the force feedback circuitry 140 may store chargesassociated with the processed time multiplexed sensed signal in order toconserve charges within the circuitry, thereby lowering powerconsumption of the circuitry.

In some embodiments, the force feedback circuitry 140 may causedetermined charges to be applied to the electrode circuitry 120 (sensingelectrode) during the forcing time period. In other words, during theforcing time period (period during which the proof mass 110 is forcedback toward its initial state), the control signal 142 causes the forcefeedback circuitry 140 to transfer the determined charges to theelectrode circuitry 120. The electrode circuitry 120 applies thereceived charges to the capacitors 112 and 114 such that the netdetected changes in the capacitors 112 and 114 is reversed. In otherwords, the application of the received charges by the electrodecircuitry 120 to the capacitors 112, 114, compensates for thedifferential charges detected during the sensing period of time andreverses, through application of electrostatic force in the oppositedirection of the original motion, the movement of the proof mass 110.For example, the changes in charges during the sensing time period isreversed during the forcing time period, e.g., net movement on the proofmass 110 is approximately zero. According to some embodiments, theapplication of the charges by the electrode circuitry 120 during theforcing time period may further cause the proof mass 110 to move, e.g.,move back to its original position prior to application of an externalactuation. Application of the charges on the capacitors 112 and 114eliminates the need to apply a high voltage drive to the proof mass 110,thereby reducing the power consumption of the sensor while stabilizingthe operation of the sensor. Moreover, the ratio of the sense and theforce pulse width is adjustable and programmable in order to optimizepower versus noise in the system. It is appreciated that according tosome embodiments, during the forcing time period, the time multiplexingcircuitry 130 may be deactivated during the time which the forcefeedback circuitry 140 applies charges to the electrode circuitry 120.

It is appreciated that during sensing time period, the time multiplexingcircuitry 130 time multiplexes the signal resulting from movement of theproof mass 110, in presence of an external actuation, that is to besensed by the sense component 135. During the sensing time period, thesense component 135 outputs the sensed signal. It is appreciated thatduring the sensing time period, the control signal 142 deactivates ordisables the force feedback circuitry 140 such that no charges areapplied to the electrode circuitry 120, contrary to the non-sensing timeperiod.

It is appreciated that while one control signal 142 is illustrated forcontrolling the operation of the time multiplexing circuitry 130 and theforce feedback circuitry 140, any number of control signals may be used.For example, one control signal may be used to control the operation ofthe time multiplexing circuitry 130 while a different control signal maybe used to control the operation of the force feedback circuitry 140. Assuch, the use of one control signal for controlling the timemultiplexing circuitry 130 and the force feedback circuitry 140 is forillustrative purposes and should not be construed as limiting the scopeof the embodiments.

Referring now to FIG. 2A, a sensor with an alternative sense circuitryin accordance with some embodiments is shown. It is appreciated thatelements with the same number as in FIG. 1 operate substantially similarto that of FIG. 1, as described above. The sensor 200A may include aproof mass 110, capacitive elements such as capacitors 112 and 114,electrodes 212 and 214, switches 232 and 234, an amplifier 250, ananalog to digital convertor (ADC) 260, a digital signal processor (DSP)270, and a digital to analog convertor (DAC) 280.

According to some embodiments, the proof mass 110 may move in onedirection or another in response to an external actuation, e.g.,rotation, force, movement, etc. For example, the proof mass 110 may moveup/down as shown by Δx. In other words, the proof mass 110 moves from afirst position to a second position in response to application of theexternal actuation. The movement by the proof mass 110 causes a changein the charges stored on the capacitors 112 and 114. For example, if theproof mass 110 moves up, then the charges stored on the capacitor 112increases, e.g., +ΔQ, while the charges stored on the capacitor 114decreases, e.g., −ΔQ. Similarly, if the proof mass 110 moves down, thenthe charges stored on the capacitor 112 decreases e.g., −ΔQ, while thecharges stored on the capacitor 114 increases, e.g., +ΔQ. It isappreciated that the change in the charges of the capacitors 112 and 114may be the same but in opposite polarity if the capacitors 112 and 114have the same capacitance value. However, it is appreciated that thechange in the charges of the capacitors 112 and 114 may merely be inopposite polarity of one another but the change in the charge may not bethe same.

During the sensing time period, the switches 232 and 234 close, therebycoupling the electrodes 212 and 214 to the amplifier 250. The output ofthe electrodes 212 and 214 is the sensed signal. The switches 232 and234 are controlled by a control signal 142. During the sensing timeperiod (period during which movement is being sensed by the proof mass110), the switches 232 and 234 close and couple the electrodes 212 and214 to the amplifier 250. The amplifier 250 amplifies the multiplexedsensed signal and outputs the amplified signal to the ADC 260 in orderto convert the signal to a digital signal. In one optional embodiment,the digital signal from the ADC 260 is input to the DSP 270 such thatthe signal can get processed, e.g., modulation, demodulation, filtering,etc. In some embodiments, the DSP 270 processes the digital signal todetermine the appropriate amount of charges to be applied through theDAC 280 during the force period of time to the electrodes 212 and 214.The output of the DSP 270 is input to the DAC 280 to convert theprocessed signal to an analog signal. It is appreciated that theoperation of the DAC 280 may be controlled by the control signal 142such that during sensing time period, no charges associated with theanalog signal of the DAC 280 is applied to the electrodes 212 and 214.

During the forcing time period, the switches 232 and 234 are opened, ascontrolled by the control signal 142, to decouple the electrodes 212 and214 from the amplifier 250. The DAC 280 may apply charges determined bythe DSP 270 during the forcing time period to the electrodes 212 and214. It is appreciated that the DAC 280 may have switches associatedtherewith to couple and/or decouple the determined charges with theelectrodes 212 and 214. The DAC 280 may be a voltage DAC or a currentDAC in some embodiments. In other words, during the forcing time period(period during which the proof mass 110 is forced back to its initialstate), the control signal 142 causes the DAC 280 to transfer thedetermined charges to the electrodes 212 and 214. The electrodes 212 and214 apply the received charges to the capacitors 112 and 114 such thatthe net detected changes in the capacitors 112 and 114 is reversed. Inother words, the application of the received charges by the electrodes212 and 214 to the capacitors 112, 114, compensates for the differentialcharges detected during the sensing period of time and reverses themovement of the proof mass 110. For example, the changes in chargesduring the sensing time period is reversed during the forcing timeperiod, e.g., net change charges on capacitors 112 and 114 isapproximately zero. According to some embodiments, the application ofthe charges by the electrodes 212 and 214 during the forcing time periodmay further cause the proof mass 110 to move, e.g., move back to itsoriginal position prior to application of an external actuation.Application of the charges on the capacitors 112 and 114 eliminates theneed to apply a high voltage drive to the proof mass 110, therebyreducing the power consumption of the sensor while stabilizing theoperation of the sensor. Moreover, the ratio of the sense and the forcepulse width is adjustable and programmable in order to optimize powerversus noise in the system. It is appreciated that according to someembodiments, during the forcing time period, the switches 232 and 234are opened while the DAC 280 applies charges to the electrodes 212 and214.

It is appreciated that during sensing time period, the switches 232 and234 time multiplex the signal resulting from movement of the proof mass110, in presence of an external actuation. It is appreciated that duringthe sensing time period, the control signal 142 deactivates or disablesthe application of charges by the DAC 280 to the electrodes 212 and 214such that no charges are applied to the electrodes 212 and 214, contraryto the non-sensing time period.

It is appreciated that while one control signal 142 is illustrated forcontrolling the operation of the switches 232 and 234 and the DAC 280,any number of control signals may be used. For example, one controlsignal may be used to control the operation of the switches 232 and 234while a different control signal may be used to control the operation ofthe DAC 280. As such, the use of one control signal for controlling theswitches 232 and 234 and the DAC 280 is for illustrative purposes andshould not be construed as limiting the scope of the embodiments. It isappreciated that the sensing period of time and the forcing period oftime may occur multiple times during any given cycle of the driveresonator oscillation.

Referring now to FIG. 2B, a sensor with an alternative sense circuitryin accordance with some embodiments is shown. It is appreciated thatelements with the same number as in FIGS. 1 and 2A operate substantiallysimilar to that of FIGS. 1 and 2A, as described above. The sensor 200Bincludes additional capacitors 287 and 289. The capacitors 287 and 289accumulate charges during the sensing period of time such that the netcharges during any sensing period of time is transmitted to theamplifier 250.

Referring now to FIG. 2C, a sensor with an alternative sense circuitryin accordance with some embodiments is shown. It is appreciated thatelements with the same number as in FIGS. 1, 2A and 2B operatesubstantially similar to that of FIGS. 1, 2A, and 2B as described above.The sensor 200C includes switches 282 and 284 and capacitors 286 and288. The DAC 280 is coupled to switches 282 and 284 that are controlledby the controlled signal 142. During the forcing period of time, theswitches 282 and 284 close to couple the DAC 280 to the capacitors 286and 288. As such, the determined charges are applied to the electrodes212 and 214 through capacitors 286 and 288 respectively. It isappreciated that during the forcing period of time, the control signal142 causes the switches 232 and 234 to open.

Referring now to FIG. 3, a sensor 300 with yet another alternative sensecircuitry in accordance with some embodiments is shown. FIG. 3 issubstantially similar to that of FIG. 2A. In this embodiment, however,the DSP 270 is replaced with demodulators 316, 318 and modulators317,319, an adder 330, quadrature loop filter 310 and an in-phase loopfilter 320, in order to track the in-phase and quadrature mechanicalinputs to the proof mass 110. The digital signal from ADC 260 isdemodulated by demodulators 316 and 318 with quadrature signal 312 andin-phase signal 314 respectively in order to correlate the timemultiplexed signal with its quadrature and in-phase components, in orderto track the quadrature and the in-phase components. The output of thedemodulator 316 is input to the quadrature loop filter 310 in order toremove the in-phase component and the output of the modulator 317 isinput to the in-phase loop filter 320. The output of the quadrature loopfilter 310 is modulated with the quadrature signal 312 using modulator317 while the output of the in-phase loop filter 320 is modulated withthe in-phase signal 314 using modulator 319. The output of themodulators 317 and 319 are summed up using the adder 330 and output tothe DAC 280. It is appreciated that the embodiments described hereinreduces sensitivity to clock jitter by utilizing a directly digitizedcarrier signal, rather than the traditional signals generated by a PLL.

Referring now to FIG. 4, a drive circuitry of a sensor in accordancewith some embodiments is shown. The sensor 410 is coupled to anamplifier 420. The amplifier 420 is coupled to ADC 430 which is coupledto a digital resonator 440. The digital resonator 440 is coupled to theinput of the amplifier 420 through a feedback loop and it may null outerror associated with the carrier frequency. The feedback loop includesa DAC 450 in series with an optional capacitor 460. The amplifier 420amplifies the drive signal and couples it to the ADC 430 that convertsthe amplified signal to a digital signal. The amplifier 420 and the ADC430 operate on residual error of the drive signal rather than the fullsignal. As such, the impact of the gain and sensitivity of the amplifier420 and the ADC 430 is reduced.

The digital resonator 440 senses digitizer loop that uses the DAC 450and a partially digital loop to digitize the drive signal, therebyrelaxing drive capacitor to voltage block's phase requirement whichreduces the impact of phase delay of the amplifier 420. The feedbackloop including the DAC 450 and the capacitor 460 cancel the incomingdrive signal, leaving an error signal to be processed by the amplifier420. It is appreciated that the feedback loop may also include abandpass digital filter to suppress the error further and to provide adigitized drive signal at the DAC 450 input.

Referring now to FIG. 5, an alternative drive circuitry of a sensor inaccordance with some embodiments is shown. FIG. 5 is substantiallysimilar to FIG. 4 except that the output of the digital resonator 440 isinput to the PLL 510 that may generates the control signal 142, asdiscussed above. It is appreciated that the digital resonator 440 mayalso be coupled to a phase shift 515 component that shifts the phase ofthe signal by 90°. The output of the resonator 440 and the phase shift515 are input to the phase adjust 517 component to adjust the phase ofthe signal and to generate the in-phase signal 314 and the quadraturesignal 312 that are used as input signals to the modulators/demodulators316-319 of FIG. 3.

It is appreciated that the resonance frequency of the resonator may bematched to the incoming drive frequency by deriving the digitalresonator parameters from the PLL frequency, locked to the drivefrequency.

Referring now to FIGS. 6A-6B, a flow diagram for low power consumptionforce feedback on the sense circuitry and drive circuitry respectivelyin accordance with some embodiments is shown. Referring specifically toFIG. 6A, a flow diagram associated with the sense circuitry of thesensor in accordance with some embodiments is shown.

Steps 610-648 occur during a sensing time period. At step 610, the proofmass is moved from a first position to a second position in response toan external actuation (as discussed in FIGS. 1-3). At step 620,capacitive charges on capacitive elements is changed in response to themovement of the proof mass (see FIGS. 1-3). At step 630, a sensed signalis generated based on the change in charges stored on the capacitiveelements, e.g., using electrode(s) of FIGS. 1-3. At step 640, it isdetermined whether the sensed signal is to be time multiplexed based onreceiving a control signal. For example, the switches and/or the timemultiplexing circuitry of FIGS. 1-3 may be used. If it is determinedthat no time multiplexing is to be performed, then charges associatedwith the time previously time multiplexed sensed signal is applied tothe sensor electrode(s), at step 650.

On the other hand if it is determined that the sensed signal is to betime multiplexed, the process may optionally go to step 642. At step642, the time multiplexed sensed signal may be amplified and convertedto a digital signal at step 644. At step 646, the sensed signal may beprocessed, e.g., modulated, demodulated, filtered, appropriate chargesbased on the sensed signal may be determined, etc. At optional step 648,the processed signal is converted to an analog signal, as described byFIGS. 1-3.

During forcing time period, at step 650, charges determined by theprocessing at step 648 is applied to the capacitive elements through thesensing electrode(s). It is appreciated that during the forcing timeperiod, the time multiplexing of the sensed signal is terminated. Inother words, the sensing by the circuitry is deactivated, e.g., byopening the switches 232-234, such that the appropriate charges can beapplied to the capacitive elements, as described in FIGS. 1-3. It isappreciated that after application of the charges, the process may bereversed such that the sensing by the sensor is once again activated andthe application of the charges to the capacitive elements isdeactivated.

Referring now to FIG. 6B, a flow diagram associated with the drivecircuitry of the sensor in accordance with some embodiments is shown. Atstep 660, the drive signal is amplified and converted to a digitalsignal at step 662, as described in FIGS. 4-5. At step 664, a resonancesignal is generated by resonating at a digital resonance frequency toreduce error. At step 666, the resonance frequency is converted toanalog signal at step 666. At step 668, charges associated with theanalog signal is stored on a capacitor, as described in FIGS. 4-5. Thus,at step 670, charges stored on the capacitor is applied to theamplifier, thereby closing a feedback loop around the amplifier and theADC, thereby reducing impact of a phase delay associated with theamplifier and the ADC, as described in FIGS. 4-5. It is appreciated thatstoring charges on the capacitor at step 668 and application of thosecharges to the amplifier at step 670 may be through components otherthan the capacitor.

Referring now to FIG. 7, an exemplary simulation of a proof mass inaccordance with some embodiments is shown. The simulation illustratesthe proof mass movement back and forth and oscillation over time untilit is brought to its initial state. For example, the proof mass may movefrom a first position to a second position when an external actuation isapplied. The circuitries, as described above with reference to FIGS.1-6B, sense the signal and close the force feedback circuitry in orderto apply appropriate charges multiple times. It is appreciated thatproof mass may be brought to a third position between the first and thesecond positions. It is further appreciated that the process may berepeated for the first position and the third position and applicationof charges during the forcing time period may bring the proof mass to afourth position that is between the first position and the thirdposition. Accordingly, the proof mass position is converged to a steadystate over time, e.g., steady state may be the first position beforeapplication of external actuation.

While the embodiments have been described and/or illustrated by means ofparticular examples, and while these embodiments and/or examples havebeen described in considerable detail, it is not the intention of theApplicants to restrict or in any way limit the scope of the embodimentsto such detail. Additional adaptations and/or modifications of theembodiments may readily appear to persons having ordinary skill in theart to which the embodiments pertain, and, in its broader aspects, theembodiments may encompass these adaptations and/or modifications.Accordingly, departures may be made from the foregoing embodimentsand/or examples without departing from the scope of the conceptsdescribed herein. The implementations described above and otherimplementations are within the scope of the following claims.

What is claimed is:
 1. A sensor comprising: a proof mass configured tomove from a first position to a second position in response toapplication of an external actuation; a drive circuitry configured todrive the proof mass into oscillation, and wherein a sense circuitry ofthe sensor to detect movement of the proof mass, wherein the drivecircuitry includes: an amplifier configured to amplify a drive signal;an analog to digital convertor configured to convert the amplified drivesignal from analog signal to digital signal; a digital resonatorconfigured to resonate at a resonance frequency to reduce error; and afeedback loop receiving signal from the digital resonator and furtherconfigured to apply a feedback signal to an input of the amplifier,wherein the feedback loop comprises a digital to analog convertorcoupled in series with a capacitor; and the sense circuitry comprising:capacitive elements configured to change capacitive charge storedthereon in response to the proof mass moving from the first position tothe second position; an electrode circuitry coupled to the capacitiveelements configured to generate a charge signal thereof; a sensecomponent coupled to the electrode circuitry configured to generate asensed signal based on the charge signal during a sensing time period;and a force feedback loop circuitry configured to apply a chargeassociated with the sensed signal to the electrode circuitry, responsiveto the control signal, during a forcing time period to change capacitivecharge of the capacitive elements to move the proof mass from the secondposition to another position, and wherein the sense component isinactive during the forcing time period.
 2. The sensor as described byclaim 1, wherein the electrode circuitry applies the charge associatedwith the sensed signal to the capacitive elements, wherein the anotherposition is a position between the first position and the secondposition, and wherein application of the charge received from the forcefeedback circuitry to the capacitive elements move the proof mass to theanother position and reduce movement of the proof mass.
 3. The sensor asdescribed by claim 1, wherein the force feedback loop circuitrycomprises a plurality of switches that open and close in response to thecontrol signal, wherein the plurality of switches closes during theforcing time period and opens during the sensing time period.
 4. Thesensor as described by claim 1 further comprising: an analog to digitalconvertor configured to convert the sensed signal to a digital signal.5. The sensor as described by claim 4 further comprising: a digitalsignal processor (DSP) coupled to the analog to digital convertorconfigured to process the sensed signal and to determine the chargeassociated with the sensed signal to be applied to the electrodecircuitry during the forcing time period.
 6. The sensor as described byclaim 5 further comprising: a digital to analog convertor (DAC) coupledto the DSP, wherein the DAC is configured to convert digital signal toanalog signal and to generate a force signal based on the determinedcharge associated with the sensed signal.
 7. A method comprising:amplifying a drive signal of a sensor using an amplifier; converting theamplified drive signal from analog signal to digital signal; resonatingat a digital resonance frequency to generate a digital drive signal;converting the digital drive signal from digital to analog signal;storing charges associated with the analog resonance signal on acapacitor; in response to an external actuation moving a proof mass of asensor from a first position to a second position, changing capacitivecharges on a plurality of capacitive elements; generating a chargesignal in response to the changing of the capacitive charges, whereinthe generating utilizes sense electrodes; responsive to a controlsignal, time multiplexing the charge signal to generate a sensed signalduring a sensing time period; determining a charge associated with thesensed signal to be applied during a forcing time period; responsive tothe control signal, applying the determined charges to the senseelectrodes during the forcing time period, wherein the sense electrodesapply the determined charges to the plurality of capacitive elements toforce the proof mass to return to its initial state; and reducing impactof a phase delay associated with the amplifier by applying the chargesstored on the capacitor to the amplifier.
 8. The method as described inclaim 7, wherein the time multiplexing is through a plurality ofswitches that close during the sensing time period and open during theforcing time period.
 9. The method as described in claim 7 furthercomprising: amplifying the sensed signal after the time multiplexing.10. The method as described by claim 9 further comprising: convertingthe amplified sensed signal to a digital signal.
 11. The method asdescribed by claim 10 further comprising: processing the digital signalto determine the charge associated with the sensed signal, wherein thedetermined charge once applied through the sense electrodes forces theproof mass to return to the first position.
 12. The method as describedby claim 7 further comprising: responsive to the control signal, openinga plurality of switches coupled to the sense electrodes during thesensing time period to decouple application of the charges to the senseelectrodes and the plurality of capacitive elements; and responsive tothe control signal, closing the plurality of switches coupled to thesense electrodes during the forcing time period to apply the determinedcharges to the sense electrodes and the plurality of capacitiveelements.
 13. A sensor comprising: a proof mass configured to move froma first position to a second position in response to application of anexternal actuation; a drive circuitry configured to drive the proof massinto oscillation, and wherein a sense circuitry of the sensor to detectmovement of the proof mass, wherein the drive circuitry includes: anamplifier configured to amplify a drive signal; an analog to digitalconvertor configured to convert the amplified drive signal from analogsignal to digital signal; a digital resonator configured to resonate ata resonance frequency to reduce error; and a feedback loop receivingsignal from the digital resonator and further configured to apply afeedback signal to an input of the amplifier, wherein the feedback loopcomprises a digital to analog convertor coupled in series with acapacitor; and the sense circuitry comprising: capacitive elementsconfigured to change capacitive charge stored thereon in response to theproof mass moving from the first position to the second position,wherein the capacitive elements include a first capacitive element and asecond capacitive element wherein the change in capacitive charge of thefirst and the second capacitive elements is in opposite polarities;sense electrodes coupled to the capacitive elements configured togenerate a charge signal thereof; a sense component coupled to the senseelectrodes configured to generate a sensed signal based on the chargesignal during a sensing time period; and a force feedback loop circuitryconfigured to apply a charge associated with the sensed signal to thesense electrodes, during a forcing time period and responsive to acontrol signal, wherein the sense electrodes are configured to apply thecharge associated with the sensed signal to the capacitive elements andreverse the change in capacitive charge on the first and the secondcapacitive elements to move the proof mass from the second position backtoward the first position, and wherein the sense component is inactiveduring the forcing time period.
 14. The sensor as described by claim 13,wherein application of the charge received from the force feedbackcircuitry to the capacitive elements reduce movement of the proof mass.15. The sensor as described by claim 13, wherein the force feedback loopcircuitry comprises a plurality of switches that open and close inresponse to the control signal, wherein the plurality of switches closesduring the forcing time period and opens during the sensing time period.16. The sensor as described by claim 13 further comprising: an analog todigital convertor configured to convert the sensed signal to a digitalsignal; and a digital signal processor (DSP) coupled to the analog todigital convertor configured to process the sensed signal and todetermine the charge associated with the sensed signal to be applied tothe electrode circuitry during the forcing time period.
 17. The sensoras described by claim 16 further comprising: a digital to analogconvertor (DAC) coupled to the DSP, wherein the DAC is configured toconvert digital signal to analog signal and to generate a force signalbased on the determined charge associated with the sensed signal.